1. Field of the Invention
The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly to a semiconductor device having a reduced leakage current and improved channel conductivity, and a method for manufacturing the semiconductor device.
2. Description of the Related Art
Research is under way to increase the operation speed and packing density of semiconductor devices. A semiconductor increases discrete devices such as a metal oxide semiconductor (MOS) transistor. As an integration degree of the semiconductor device is increased, scaling down a gate of the MOS transistor is becoming a major challenge. In addition, a channel region located under the gate becomes shorter.
Accordingly, various methods are investigated to enhance channel conductivity by increasing the mobility of carriers in a channel region with respect to a predetermined channel length. One mechanism for increasing the mobility of carriers is to induce compressive stress to a channel region to thereby increase hole mobility in the channel, while inducing tensile stress to the channel region to improve electron mobility in the channel region.
The stress memorization technique (SMT) is one technique that has recently been used to induce stress to a channel, which may, however, result in an increase of leakage current.